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inois State Geological Survey
addresses challenges for a healthy
economy and a healthy environment
LIBRARY.
inois State Geological Survey
addresses challenges for a healthy
economy and a healthy environment
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From the Chief
Research at the Illinois State Geological
Survey (ISGS), a division of the Depart-
ment of Energy and Natural Resources
(ENR), strengthens the state's economy by
encouraging sound exploration, logical
development, and intelligent use of mineral
resources. At the same time, the Survey's
efforts are directed toward providing
geological information vital for developing
judicious environmental policies to protect
and enhance the health, safety and well
being of Illinois' citizens.
Earth-related sciences will continue to
play an evermore important role in resolv-
ing the multitude of complex environmental-
and resource-related issues facing the
state. ..nation. ..and world. This annual
report, prepared especially for the general
public, presents three major issues and the
Geological Survey's research and service
programs and projects which respond to
those concerns. The period covered is Fis-
cal Year 1991, extending from July 1, 1990,
to June 30, 1991.
At issue is the ability to provide an ade-
quate supply of domestic petroleum for
transportation fuels, one of the most
serious short- and long-term energy
problems for the country today. Of major
concern are the ongoing developments in
the oil industry that have had a nationwide
impact on research efforts, domestic oil
production, and economic development in
oil-producing states. Imports for the past
couple of years have approximated 50 per-
cent of the nation's supply of crude oil and
petroleum products, placing the United
States in a steadily worsening economic
position, while increasing concerns for
security of supplies.
While Illinois' oil production has de-
creased sharply from 30 million to under 20
million barrels of oil a year, large quantities
of discovered oil remain trapped within al-
ready discovered reservoirs. Only about
35 percent of the oil-in-place has been
produced, leaving 1 .4 billion barrels of oil
as by-passed mobile oil and another 4.5 bil-
lion barrels as residual oil. A major effort is
under way at the ISGS to find economic
ways to get more of this oil out of the
ground. Our scientists are determining
which methods of improved recovery work
best for the wide range of conditions exist-
ing in Illinois' oil fields. A segment of this
report focuses on this research and the
means by which the Survey is transferring
the results and knowledge gained to the oil
industry in this state....
At issue is protecting Illinois'
groundwater from contamination. The
ISGS is very actively involved in meeting
mandates of the Illinois Groundwater
Protection Act by conducting pertinent map-
ping, assessments, monitoring, and techni-
cal assistance programs in support of the
protection and preservation of ground-
water's quality as well as the management
of this vulnerable resource. Approximately
two-thirds of the state's population depend
on groundwater as a source of supply. In a
number of cooperative efforts highlighted in
this report, the Geological Survey's scien-
tists have been working to evaluate the im-
pact of agricultural chemicals (pesticides
and nitrates) on groundwater, particularly in
rural areas where they are most intensively
used....
At issue is the need for but absence of
detailed geological mapping for about 97
percent of Illinois to address environmental-
and resource-related issues that face the
state at regional and local levels. Detailed
geologic maps and other studies of re-
gions, counties or smaller units provide
state and regional planners, county boards,
public health departments and citizens with
information about the Earth's surface and
the materials that lie beneath it — informa-
tion required to sustain economic develop-
ment and protect the environment.
Almost every area of the state faces
problems with waste disposal, groundwater
protection, and the environmental effects of
normal human activities. Detailed geologi-
cal information is required to ensure maxi-
mum protection from possible contamina-
tion of our supplies of groundwater and sur-
face water; to ensure that major highways,
railroads, factories, schools and other facil-
ities are constructed on sites that provide
adequate support for foundations and are
free of threats from flooding, landslides,
and other man-caused and natural earth
hazards; and to guide officials in deciding
the direction of future economic develop-
ment.
Although much is known about the geol-
ogy of Illinois at statewide and regional
scales, "detailed" geological maps are avail-
able for only a few limited areas. Thus, a
program of detailed geological mapping is
required to provide the necessary geologic
information to cover important state and
regional concerns. A segment of this
report is devoted to the mapping needs of
the state and the nation and the manner in
which a program of this magnitude is at-
tainable.
While this annual report highlights only
three issues and respective ongoing re-
search and service programs at the ISGS,
the scope of the Survey's efforts is far
wider, affecting jobs and economic growth,
environmental protection, energy security,
access to minerals and clean water, ap-
propriate use of land, proper siting of
facilities and infrastructure, agriculture, and
public safety and health. For a more in-
clusive look at the ISGS' research and ser-
vice pursuits, please request a copy, free of
charge, of the "Illinois State Geological Sur-
vey: Science focusing on issues and
trends; future needs." Should you wish
more comprehensive, technical informa-
tion, I invite you to request a copy of the
Survey's scientific annual report.
Research Aimed at Improved Oil
and Gas Recovery
Consider the fact that Illinois, 15th in oil out-
put in the United States, produced almost
30 million barrels of oil just five years ago
and now produces just under 20 million bar-
rels of oil a year. Yet, research at the
Geological Survey indicates that almost
two-thirds of the discovered oil remains
trapped within the reservoirs in the subsur-
face. In fact, the U.S. Department of Ener-
gy (USDOE) estimates that Illinois has 6.0
billion barrels of this unproduced oil. Much
of this oil is residual, immobile oil that may
be produced only with great difficulty and at
prices considerably higher than today's
prices. But about 1 .5 billion barrels of this
unproduced oil remains as mobile, by-
passed oil in untapped compartments due
to heterogeneities in the rocks in the sub-
surface. Some of this oil can be recovered
using today's technologies and at today's
Donald Oltz, senior geologist and head of the Oil and Gas Section,
assists Dennis Haggerty, petroleum engineer, in taking a plug from
an outcrop of the Aux Vases Sandstone. Scientists will study the
porosity, permeability and other characteristics of this sample and
compare them with geologic information from subsurface reservoirs
in the same rocks.
prices if only we could better understand
and predict the factors causing the com-
partmentalization.
Additionally, many wells in Illinois, which
initially produce hundreds of barrels of oil
per day, exhibit a production decline to less
than 10 barrels a day (a stripper well).
Caused in some cases by formation dam-
age, this rate of decline can make wells un-
economical and discourages investments.
Improved oil recovery is possible. It is
needed.
While Americans' consumption of
hydrocarbons, particularly those used for
transportation fuels, continues its upward
spiral, U.S. production declines — a trend
since the collapse in oil prices in 1986. At
an accelerated pace, major U.S.-based oil
companies are shipping their capital for ex-
ploration and development overseas. Tens
of billions of dollars that once would have
been spent to drill wells or build refineries
in this country are being earmarked for
foreign operations. According to an
analysis of 18 domestic companies by
Petroleum Finance Co., the U.S. share of
all their spending for exploration and
development dropped from 60 percent in
1 985 to 20 percent in 1 990. Inevitably, the
result will be a further decline in domestic
oil production and increased dependence
on imports, not just for crude oil but for
refined products such as gasoline and jet
fuel as well. Estimates indicate this country
will import an average of 47 percent of its
oil and gas in 1992.
While this trend will continue, geological
investigations have shown that some things
can be done at home to reduce the rate of
decline and help in the event of another oil
crisis. Work by the Illinois State Geological
Survey, now in the third year of a program
designed to increase Illinois' oil resources
and prudently develop them, has con-
tributed to the results of these investiga-
tions. This program of improved oil
recovery has been recognized as fitting in
well with the objectives of the National
Energy Strategy, which emphasizes the
domestic oil supply and a reduction of im-
ports.
To help increase oil recovery and aid
economic development of the depressed oil
industry in the state, the ISGS has an in-
tegrated, multidisciplinary team of geol-
ogists, reservoir engineers, geochemists,
clay mineralogists, and computer experts
analyzing and assessing oil reservoirs and
studying the impact of reservoir heteroge-
neity on oil production. Goals of this major
effort are to aid Illinois' independent oil
producers in the recovery of higher percent-
ages of oil from fields already discovered,
develop new incentives to encourage ex-
ploration, promote logical development of
Illinois' oil and gas, and provide relevant
and timely information to the oil industry
and the public through technology trans-
fer— a major component of the project.
Through outreach programs and work-
shops, which have already begun, re-
searchers hope to encourage producers to
apply promising techniques in drilling, com-
pleting, maintaining and managing reser-
voirs to maximize hydrocarbon recovery.
Program heralded, studies
15 fields
Representatives from industry and the
USDOE have heralded the Geological
Survey's four-year, $4.9 million program as
a model. This matching state-federal
cooperative venture is already providing in-
formation on hydrocarbon resources, reser-
voir characteristics, production methods
and reservoir management. Researchers
have made substantial progress in their
pilot studies of the type and degree of reser-
voir heterogeneity in 15 fields producing
from two of Illinois' most prolific oil-produc-
ing horizons, the Cypress and Aux Vases
formations, and have already begun to
publish their results.
To unlock the secrets to more efficient
oil recovery in these horizons, the geol-
ogists are using many "tools"— from simple
saws, grinders, and drills to seismic ex-
perimentation and a multitude of sophisti-
cated instruments, including testing
equipment, simulators, and workstations
providing computerized graphics. Through
thorough, intensive probings in the field
and laboratory or at a computer and draft-
ing table, they are getting a foothold on
Petroleum
geologist Bob
Cole labels a
core sample
of Cypress
sandstone.
potential problems and conditions within
reservoirs capable of impeding recovery of
Illinois' oil.
To achieve a greater understanding of
the hydrocarbon reservoirs, staff members
have also undertaken an investigation of
the features found in these same rock inter-
vals exposed at the surface. They com-
pleted a statewide surface investigation of
the Aux Vases Formation in 1990 and sub-
sequently began a similar investigation on
the Cypress Formation wherein the re-
searchers are recording detailed observa-
tions and measurements and collecting
samples for microscopic and other evalua-
tions; thereafter, the geologist responsible
for compiling the information is interpreting
results.
In one specific aspect of this study, the
scientists are making a highly detailed in-
vestigation of an extensive Cypress out-
crop located on Interstate 57 near Anna.
They are treating this outcrop as an analog
of a petroleum reservoir, gathering informa-
tion on an inch-by-inch basis. The scien-
tists are describing the exposure in great
detail and using sophisticated instrumenta-
tion to determine the permeability of the
rocks (a measure of the ability of fluids to
move through the rocks) as well as the
amount of low-level gamma ray emissions
from the rocks (indicative of how clean the
sands are). With a high-powered drill, they
are also taking samples for further testing
in the laboratory. Results are then being
compared with similar information gathered
from selected oil-producing horizons in the
subsurface.
In addition, staff members are compiling
data from chosen wells in the oil-producing
area of the state to be used in a regional
study of the relationships among outcrops,
subsurface stratigraphy and hydrocarbon
reservoirs. Cross sections, showing
stratigraphic changes within these forma-
tions, and maps, showing reservoir distribu-
tion, will be constructed.
Technologies extrapolated
to similar reservoirs
The Survey's geologists are also studying
the composition of a reservoir using core
samples examined by X-ray diffraction to
determine the kinds and relative quantities
of clay minerals present, which are often
troublesome in oil recovery, and a Scan-
ning Electron Microscope to determine the
distribution and shape of pores in the rocks
Steve Sim, petroleum engineer, demonstrates a new state-of-the art
pressure, volume and temperature (PVT) apparatus that simulates
oil-production conditions in the laboratory. When oil is brought to the
surface, a change in pressure, volume and temperature causes
some oil loss in the form of gas. The ISGS can help oil producers
calculate this loss with PVT equipment, which measures the de-
crease in the volume of oil as it comes to the surface and the amount
of gas released at the surface. With the PVT, researchers can simu-
late carbon dioxide injections (used to enhance oil recovery) and
measure oil swelling and viscosity reduction at reservoir temperature
and pressure and calculate the potential increase in production.
Fluid analysis data are useful for estimating oil and gas reserves in
the reservoir, designing surface oil and gas separation equipment,
planning production strategy and for enhanced oil recovery.
comprising the reservoir. Regionally, they
are correlating these analyses with inter-
pretations of similarities in depositional
processes, reservoir geometries, and
wireline log responses of reservoir rocks.
To date, results indicate that similar
modifications during and after deposition
are responsible for development of reser-
voir characteristics in the Aux Vases over
specific areas being studied. Knowledge of
reservoir similarities will permit testing and
subsequent extrapolation of specific tech-
nologies for improving oil recovery to other
reservoirs.
Knowing the type of rock and clay
minerals and their areal distributions across
a reservoir are important factors for
developing an optimal recovery system.
Researchers have detected significant dif-
ferences in clay content, types of clay
minerals and cementing minerals that af-
fect a well's productivity and, therefore,
should be considered during drilling and
completion. For instance, clays subjected
to a fresh-water drilling mud may swell and
plug rock pores, cutting off porosity and per-
meability, thereby diminishing oil recovery.
In addition, acids, normally used to stimu-
late production or remove excess casing ce-
ment, can also harm recovery by reacting
with certain clay minerals. Clay-mineral
particles, when dislodged, can plug up
pores. Forewarned, a producer can take
appropriate measures while developing a
reservoir/field.
Using other state-of-the-art apparatus,
researchers in the ISGS' laboratories are
flooding core samples from reservoirs with
hydrochloric acid, different brines, fresh
water, or other chosen fluid desired and are
studying reactions to determine any pos-
sible mischief these substances can cause
in a given reservoir. The fluids chosen for
this research effort simulate those normally
used in Illinois' oil fields. Then too, staff
members are looking at reservoir fluids to
predict reactions that influence porosity and
permeability and changes in reservoir prop-
erties in response to the injection of fluids
used in enhanced oil recovery. During this
period, they have collected 39 samples of
brine and oil from the Aux Vases and Cy-
press formations and are analyzing them
for various physical and chemical attri-
butes. The data will be used for computer
modelling to forecast formation damage
from the use of certain fluids.
In other experiments, also under simu-
lated reservoir conditions, researchers vary
pressure, volume and temperature of dif-
ferent oils to learn the optimal parameters
for estimating oil and gas reserves and
planning production strategies as well as
for enhanced oil recovery studies such as
the effects of injecting carbon dioxide into a
reservoir.
Visuals (a variety of geologic maps,
cross sections, well logs, photos of mineral
deposits taken from microscopic/analyzer
examinations of core samples, three-
dimensional computer modelling of the
subsurface, etc.) are very important to this
This three-D
display shows
changes in pres-
sure in the oil-
producing
formation over a
period of time.
research, allowing observations of the
many complexities within a reservoir.
Computer imaging capabilities permit re-
searchers to see a reservoir take shape
layer by layer, study the distribution of the
sands, strip away non-reservoir rock, and
filter information any way they choose. In
fact, with such a graphic tool, they can strip
out the characteristics desired, move them
into a reservoir simulator, simulate a water
flood with wells at various spacings, and ob-
serve the results — all from their worksta-
tions at the ISGS.
Thus far, the Survey's geologists have
defined the types of reservoirs and charac-
teristics of each, looked beyond deposition-
al environments to post-depositional factors
that have affected the reservoirs, and are
learning how characteristics affect recovery
of hydrocarbons. Because of compartmen-
talization, they have confirmed a need to
alter Illinois' 10-acre well spacing when by-
passed oil can be ascertained by geologic
and engineering studies. The scientists
have documented that clays are important
factors within these reservoirs. Major
Using the new Silicon
Graphics workstation,
Emmanuel Udegbunam,
petroleum engineer, at
left, and Hannes Leetaru,
petroleum geologist, take
the results of oil-field
studies into the next re-
search phase: modelling
reservoir characteristics
and production data via
three-dimensional color
graphics.
players in reservoir damage, clay minerals,
if not handled properly, are often detrimen-
tal to the recovery of oil.
Focused studies, results
Examples of the results to date are
provided by the following brief reviews of in-
tegrated studies of the Tamaroa, Bartelso
and King fields. Tamaroa Field, which
produces from the Cypress Sandstone, has
been studied to evaluate the potential to in-
crease its cumulative oil production and
define recovery problems. Discovered in
1942, this field, located in northeast Perry
County, produces just below 1 ,100 feet,
principally from multiple lenticular stacked
sandstones, separated by shales. Based
on records of 32 of the 46 producing wells,
the Tamaroa and Tamaroa South fields
produced some 770,000 barrels through
1989, but only a few wells in Tamaroa
South remain in operation today.
Comparison of the separate pools in this
area shows similarities in the physical char-
acteristics of the sandstone bodies. Scien-
tists believe the depositional processes and
settings for the sandstones were also likely
similar. Intuitively, one might expect similar
recovery efficiencies, but this has not been
the case.
Within the multiple oil reservoirs of the
Tamaroa and Tamaroa South fields, both
marginal and successful production pro-
grams are apparent. Efficiencies in recov-
ery have varied widely. For example, the
Tamaroa Field, developed in two stages,
had recovery efficiencies of five percent in
the initial wells (attributable, in part, to
release of gas pressure from the reservoir)
to 43 percent, achieved by primary (pump-
ing) and coordinated secondary (water
flooding) recovery methods. Tamaroa
South, also developed in two stages,
achieved 25 and 32 percent efficiencies
using some water flooding.
The variable recovery is a result of reser-
voir heterogeneity, an understanding of
these complexities, and the subsequent
manner in which these fields have been
managed. Reservoir management should
be a combined program through all stages
of drilling, completion, stimulation and
development. Research indicates that
more can be done to wisely produce these
fields.... The study found that improved oil
recovery techniques can increase produc-
tion for the field by using developmental
drilling; pressure maintenance; coordinated
secondary (water flood) recovery pro-
grams; and where compartmentalization
exists, different well-spacing practices.
Bartelso's development
well managed
Another study detailing the rocks and struc-
tural factors that affect reservoir develop-
ment and hydrocarbon recovery from
sandstones in the Cypress Formation is
In the geologic model, a three-dimensional grid of cross sec-
tions (fence diagrams) is superimposed on a projection of
wells drilled into the Aux Vases Sandstone, an oil-bearing
reservoir. Rotating the grid, petroleum geologists can change
the perspective of the subsurface rock formations, and using a
zoom control, they can look at by-passed portions of the forma-
tions from which the oil has not been recovered.
that of the Bartelso Field, discovered in
1936, in south-central Clinton County. The
management of this field represents a suc-
cess story inasmuch as 50 percent (about
2.5 million barrels) of the oil has been ex-
tracted from 76 wells compared to one-third
efficiency of recovery achieved by employ-
ing normal primary and secondary produc-
tion methods in most reservoirs in the Il-
linois Basin. Well-coordinated water flood-
ing covering multiple leases throughout the
entire reservoir and varied well spacing
were key elements in the high level of
recovery at Bartelso.
The upper sandstones in the Cypress at
Bartelso are shingled bars and the primary
reservoir. The Cypress in that field has
been subdivided into four separate sand-
stone intervals, the upper three of which
contain oil and gas. Researchers have
found that only the lowermost producing
sandstone exhibits sufficient homogeneity
to be efficiently drained with a 10-acre well
spacing. Because of the complexities in
the upper two producing units, closer well
spacing was needed to optimize recovery.
Illinois' 10-acre well spacing for sand-
stone reservoirs was arbitrarily established
with no geologic basis. Reservoirs deeper
than 4,000 feet require an arbitrary 20-acre
spacing, according to regulations. Such
spacing criteria are waived with water flood-
ing, allowing tighter spacing at Bartelso,
where compartmentalized oil in the upper
two producing units would have been
missed otherwise. This study, in itself,
points out the need for strategic infill drilling
based on geology rather than arbitrary
spacing.
Looking at the Survey's study of the
King Field, one learns that the productive
Aux Vases sandstone was formed in a
nearshore, marine environment similar to
the Bartelso Field. The King Field, located
five miles southeast of Mt. Vernon, in Jeffer-
son County, extends over 1 ,700 acres. It
produces mainly at a depth of about 2,750
feet, although there is minor production
from overlying and underlying reservoirs.
From the original 17 million barrels of oil in
place, 108 wells have produced 4.1 million
barrels since 1942.
Although depositional environments
were similar between the King and Bartelso
fields, their efficiencies of recovery are
quite different, King having less than 30 per-
cent versus the 50 percent attained at Bar-
telso.
Post-depositional alterations occurred in
the King reservoir, causing a high degree
of reservoir heterogeneity. Chemical
properties of the rock reservoir were al-
tered. For instance, scientists found more
clay and calcite in the reservoir at King
than Bartelso. Calcite cement and clay
made recovery of oil from the King Field
more difficult. These influences on reser-
voir heterogeneity as well as compart-
mentalization resulting from depositional
conditions were not understood when
recovery methods were applied.
As production steadily declined after
1966, there were no new water floods, out-
posts or infill wells. In fact, most of the
wells were plugged and abandoned after
the collapse of oil prices in 1986.
Significant areas unswept
Abandonment may have been premature,
according to the Survey's researchers.
Their study shows that compartmentaliza-
tion in the reservoir at King Field has al-
lowed significant areas to remain unswept
by recovery efforts using water flooding.
An estimated one to two million barrels of
oil may be recoverable by primary and
water-flood methods. Data, which will help
implement improved or enhanced oil
recovery techniques in this oil field, and
areas where these techniques should be
applied are presented in a report already
released by the ISGS entitled "Reservoir
Heterogeneity and Improved Oil Recovery
of the Aux Vases (Mississippian) Formation
at King Field, Jefferson County, Illinois."
Scientists at the Geological Survey
believe that geologically-targeted infill drill-
ing between existing wells combined with
selective, well-designed water flooding may
be able to recover up to 1 5 percent of the
remaining primary reserves in the King
Field.
Based upon such current studies, the
Illinois State Geological Survey is develop-
ing an understanding of reservoir hetero-
geneities and the implications of reservoir
management to handle these variations.
Through seminars, workshops, poster ses-
sions, and invited talks, staff members are
already sharing much of this new know-
ledge with those who can put it to good use
in the oil fields. Such technology transfer
to operators and other representatives of
Technology transfer is pic-
tured with Kenneth McGee,
petroleum geologist, pointing
out a Cypress Sandstone
reservoir to an oil producer.
During a workshop, scientists
presented and displayed in-
termediate results of field
studies on the Cypress and
Aux Vases formations in the
Illinois Basin to independent
oil producers.
the oil industry in Illinois has occurred a
number of times during this reporting
period. The scientists presented invited
talks describing this research to members
of the Illinois Oil and Gas Association, Il-
linois Oil Producers Association, the Ken-
tucky Oil and Gas Association, the Illinois
Stripper Well Owners and Royalty Associa-
tion, the Eastern Section of the American
Association of Petroleum Geologists
(AAPG), the Fifth International Archie Con-
ference, and the Illinois Geological Society.
In addition, the researchers have pre-
sented poster-style displays, showcasing
their work at the Illinois Oil and Gas Asso-
ciation's annual meeting, attended by some
400 local geologists, oil company opera-
tors, and service company representatives.
Exhibits were also presented at the
AAPG's national meeting, attended by
more than 6,000 national and international
representatives of the petroleum industry,
and the Eastern Section meeting of AAPG.
The payoff for employing enhanced
recovery techniques suggested by this re-
search is handsome. Consider the fact
that the state's 1 990 oil production of
1 9,900,000 barrels had a value of more
than $398 million at $20 a barrel. Of the es-
timated 6.0 billion barrels of by-passed oil
left in reservoirs across the state, some 1 .5
billion barrels represent mobile recoverable
oil. If the application of technology
developed during this program resulted in
an increased production of 1 0 percent of
these 1 .5 billion barrels of unswept mobile
oil, at $20.00 a barrel, the value of in-
cremental production in Illinois could equal
$3.0 billion....
And if the application of this technology
opened up Illinois' oil fields, other positive
ramifications would accrue such as an im-
proved economy in the depressed oil-field
areas of Illinois.
Protection Crucial to Groundwater's
Quality, Usability
Water, although a necessity for all living
things, is also a key to future economic
growth. While its use in this country over
the past 40 years has more than doubled,
this vital resource has been and remains
very vulnerable to contamination.
Will there be water for future genera-
tions? Will it be suitable for consumption?
How will water be protected from human ac-
tivities that could be spoiling its use?
While not fully funded, the Illinois
Groundwater Protection Act mandates ac-
tivities that will provide information to help
balance protection and use of the ground-
water resource. It calls for developing a
coordinated groundwater data collection
and automation system, including results of
groundwater monitoring and collection of
well logs, pollution source permits, and
water quality assessments; developing and
administering ongoing basic and applied re-
search; and making results and information
available to local governments seeking as-
sistance. Activities, to be carried out by the
Department of Energy and Natural Resour-
ces (ENR), of which the ISGS is a division,
include the following:
1 . long-term statewide groundwater moni-
toring;
2. statewide assessments of groundwater
resources to enhance the data base by
locating resources, mapping aquifers, iden-
tifying appropriate recharge areas, and
evaluating base line water quality;
3. evaluating the impact of pesticides on
groundwater; and
4. other basic and applied research, includ-
ing groundwater hydrology and hydraulics,
movement of contaminants, and technolo-
gies for the restoration and remediation of
aquifers.
On the left, Dennis McKenna, geologist in the Ground-
water Protection Section, uses a baler to remove
groundwater samples from a monitoring well located
next to a stream. Above, he purges the monitoring well
before obtaining a fresh sample that is more repre-
sentative of the water found in the aquifer.
For their study of groundwater's contamination by atrazine, scientists found this farm south of Urbana that met all
of their criteria: corn and soybeans in rotation, presence of a tile-drainage system, past and current use of
atrazine, relatively uniform soil and geologic conditions, co-location with existing water quality studies by state or
federal agencies, and cooperation of the landowner.
Among programs that have received
funding are ones investigating the impact of
pesticides on groundwater and ground-
water assessments. Concern over the
potential for contamination of groundwater
by agricultural chemicals is founded on the
following facts:
• Two out of three acres of rural Illinois
are treated with agricultural chemi-
cals— some 50 million pounds of pes-
ticides and a million tons of nitrogen
fertilizer annually.
• More than 80 percent of the corn and
nearly 30 percent of the soybean
acreage receiving preplant or preemer-
gent weed control in 1 990 was treated
with herbicides that pose a potential
hazard to groundwater in vulnerable
soil and hydrogeologic settings.
• Groundwater is the only source of
drinking water for about 97 percent of
the rural population in this state.
• Aquifers occur within 50 feet of the
ground's surface in about 40 percent
of rural Illinois.
• State and county agencies have
detected pesticides in samples of
groundwater from shallow aquifers.
However, public water wells that nor-
mally withdraw water from deep
aquifers apparently have not been
significantly affected.
Thus, accurate prediction of the vulner-
ability of groundwater resources to contam-
ination from agricultural chemicals (pesti-
cides and nitrates) is one of the most impor-
tant environmental issues facing farmers,
water users and governmental agencies.
With current agricultural practices and tech-
nology, leaching of agricultural chemicals—
particularly nitrates derived from fertilizer
nitrogen and the more mobile pesticides —
into groundwater may be impossible to
prevent. Areas most vulnerable to con-
tamination must be identified to effectively
target educational programs, technical as-
sistance, and detailed monitoring studies of
groundwater resources in the state.
Regulation of the use of agrichemicals
must also take into account the vulnerabil-
ity of groundwater resources. The USEPA
has published a strategy to regulate the
use of pesticides to prevent unacceptable
levels of contamination in current and po-
tential supplies of drinking water. It recom-
mends managing the use of pesticides on
the basis of differences in the use of ground-
water, its value and vulnerability. The agen-
cy also recommends using the vulnerability
of groundwater as a basis for county- or
state-level measures, which may include
cancelling the use of specific products.
If water is under protected, it may be-
come contaminated, detrimentally affecting
users. On the other hand, over protection
of this resource could result in restrictions
in areas that do not require stringent protec-
tive measures, resulting in economic hard-
ship. Thus, an optimum level of protection
for groundwater should balance the use of
11
12
agricultural chemicals and protective meas-
ures. Research relating to the effects such
chemicals are having on Illinois' aquifers is
under way at the ISGS.
In support of the state's Pesticide Man-
agement Plan being developed by the Illi-
nois Department of Agriculture (IDOA), the
Geological Survey's scientists are using
knowledge of groundwater flow, soil and
rock/water interaction, and statewide geo-
logic maps to identify regions with aquifers
vulnerable to contamination by agricultural
chemicals.
Precipitation,
source of groundwater
Illinois' source of groundwater is precipita-
tion that infiltrates the soil and percolates
downward to the water table. The replenish-
ment of groundwater, known as recharge,
depends upon the moisture conditions of
soil, its permeability and water retention
capacity, type and distribution of vegeta-
Zhenkun Zhao, left, and Lettie Schmitt, both lab assistants in the Geo-
logical Survey's Environmental Geology Laboratory, are measuring
the uptake of pesticides by soil.
tion, duration and intensity of precipitation,
and location within the groundwater-flow
system. Regionally, the interrelationship of
surface soils, underlying geologic materials,
and configuration of the landscape deter-
mines the rate and amount of recharge and
the direction of shallow groundwater flow.
Tile-drainage systems in agricultural areas
may alter natural drainage and recharge.
Recharge does not occur at specific points
or in small areas; some recharge occurs in
all unpaved areas except the discharge
areas. Streams in Illinois that flow all or
most of the year are groundwater-discharge
areas. Water will infiltrate to the water
table over the entire interstream area;
some water will move upward through
evaporation from the soil and transpiration
from plants, while the remainder will move
downward into the saturated zone. Some
of this water will discharge into nearby
streams with the remainder moving deeper
into the regional groundwater-flow system.
The movement of groundwater is direct-
ly related to the permeability of geologic
materials and the hydraulic gradient. In
areas directly underlain by permeable bed-
rock or sand and gravel, relatively rapid in-
filtration and movement will occur. How-
ever, in areas underlain by silty or clayey
materials, surface runoff may be greater
and the movement of groundwater general-
ly slower, providing considerably less
recharge to aquifers than in areas com-
posed of sand and gravel or permeable
bedrock at or near the surface. Thus, the
vulnerability of an aquifer is estimated on
the basis of the thickness and character of
materials overlying it. The character of the
materials affects the rate of movement and
the degree of attenuation (reduction in the
concentration of a pesticide); the thickness
affects the time to reach an aquifer, allow-
ing more time for attenuation.
For the project with IDOA on identifying
regions with aquifers vulnerable to con-
tamination from agricultural chemicals, the
Survey has mapped Illinois at a scale of
1 :500,000 (one inch equals approximately
eight miles). It is also providing county
maps developed at 1:250,000 (one inch
equals approximately four miles). A report
will accompany each map and summarize
the factors and processes affecting the
transport of agricultural chemicals to
groundwater resources.
The interpretive maps are based on the
distribution of the Earth's materials. Highly
permeable materials (sands, gravels, frac-
tured carbonate rocks, and sandstones) will
generally allow rapid migration of contamin-
ants. Materials of relatively low permeability
(loess, glacial till, shales, cemented sand-
stone, and unfractured carbonate rocks)
generally restrict contaminant migration.
Thickness of fine-grained materials controls
the susceptibility of the underlying aquifers
to contamination; the thicker the sequence
of fine-grained material between the source
and the aquifer, the less likely the aquifer
will become contaminated. In addition, the
concentration of a chemical may be re-
duced by natural processes (degradation,
dilution, adsorption) before it reaches an
underlying aquifer.
In the Environ-
mental Geology
Laboratory, Bill
Roy, geochemist,
examines an ex-
tract of a soil
sample.
Distribution of
geologic deposits
To map the potential for contamination of
aquifers by agricultural chemicals, scien-
tists used geologic information compiled
from the Stack-Unit Map of Illinois publish-
ed in 1988 by the ISGS. (The mapped
units depict the distribution of geologic de-
posits vertically from the surface to a depth
of 50 feet as well as horizontally over a
specified area.) Staff members combined
sequences of materials into four groups dif-
ferentiated on the basis of distance from
the land's surface to the top of the first con-
tinuous deposit of aquifer materials. In
addition to the nature of earth materials,
other factors, including the amount and
properties of a given chemical and climatic
factors, also need to be considered in deter-
mining the ultimate potential for contamina-
tion.
According to the maps and report pre-
pared for the study entitled "Potential for
Agricultural Chemical Contamination of
Aquifers in Illinois," areas with intensive
corn and soybean production and aquifer
materials within 50 feet of the Earth's sur-
face are most vulnerable to contamination.
Scientists based this interpretation on their
present understanding of the persistence of
pesticides and rates of groundwater move-
ment coupled with the results of studies on
pesticides made in Iowa and Minnesota,
which showed that pesticides were most
commonly detected in shallow aquifers.
In approximately 40 percent of rural
Illinois, aquifers lie within 50 feet of the
ground's surface. These shallow aquifers
occur throughout the state but are most
common in the northern and southern parts
Phil Reed, geologist in the Hydrogeology Sec-
tion, lowers a sonde into an observation well
to determine the sequence of earth materials.
and along the major river valleys. In about
60 percent of Illinois' rural areas, aquifers
are more than 50 feet deep and apparently
protected from contamination by agricul-
tural chemicals by the attenuation capacity
(all physical, chemical and biological pro-
cesses that reduce the concentration of a
pesticide) of soils and thick sequences of
fine-grained materials. The use of pesti-
cides, largely for corn and soybean produc-
tion, is heaviest in areas of Illinois where
aquifers are generally least vulnerable to
contamination....
Additionally, in response to mandates of
the Illinois Groundwater Protection Act for
ENR to carry out basic and applied ground-
water research, scientists from the ISGS
and the Illinois State Water Survey (ISWS),
in cooperation with the IDOA, are conduct-
ing a pilot study to evaluate the impact of
pesticides and nitrates on groundwater in
five representative hydrogeologic settings
in the state. While providing a preliminary
estimate of the occurrence of agricultural
chemicals in rural private water supplies,
the pilot program is helping evaluate com-
ponents of a recommended statewide sur-
vey for agricultural chemicals in rural wells.
Besides evaluating analytical methods,
the study has tested procedures to inven-
tory sites of wells, conduct interviews with
users of the wells, and collect water sam-
ples. Sampling of 48 randomly-selected
rural water wells was completed in Febru-
ary 1 991 . Analysis of 240 water samples
taken from these wells for 39 agricultural
chemicals extensively used in Illinois (par-
ticularly pesticides with a high potential to
move through the soil), nitrate, and nitrite
were completed during the year. Using the
USEPA's methods employed in the Nation-
al Pesticide Survey, the ISGS determined
20 of the compounds, while the ISWS and
Department of Agriculture analyzed other
compounds. Reports describing the char-
acterization process and the overall project
are in preparation for the funding agen-
cies—the Illinois EPA (IEPA) and ENR.
This project will establish base line data
for pesticides in groundwater in several
hydrogeologic settings and will help evalu-
ate criteria for predicting the potential for
contamination of rural wells. If scientists
can more accurately estimate the occur-
rence of agricultural chemicals in wells in
various hydrogeologic settings, they may
be able to develop a tailored sampling pro-
gram that can better characterize and fore-
cast potential problem areas as well as
result in a more cost-efficient sampling ef-
fort statewide. From these results, other
agencies could target educational and
monitoring programs for groundwater to
areas of greatest need....
Base line studies
In a separate study, in accordance with
mandates of the Illinois Groundwater Pro-
tection Act and in response to the public's
concern over potential contamination of
groundwater by agricultural chemicals, the
IDOA, the state's lead agency for pesticide
regulation, initiated a survey to provide
statistically reliable estimates of the occur-
rence of agricultural chemicals in rural,
private water wells in the state. Of the es-
timated 440,000 private water wells in Illi-
nois, approximately 360,000 are in rural
areas.
The Geological Survey is cooperating
with the Department of Agriculture and the
Cooperative Extension Service of the
University of Illinois at Urbana-Champaign
in this statewide project in which ground-
water samples are being collected from ap-
proximately 340 randomly-selected wells
and analyzed for nitrate, nitrite, a number
of pesticides and metabolites. Sampling
began in March 1991.
Primarily responsible for development of
the sampling plan and procedures for col-
lecting samples, the ISGS is also providing
Ivan Krapac, geochemist, spikes a field sam-
ple of groundwater with a known concentra-
tion of a pesticide for which analyses will be
made in the laboratory. These spiked sam-
ples check on the accuracy of lab analyses.
geologic characterization of the areas in
which samples are being collected and will
assist in interpreting the final results. Rela-
tionships among the quality of well water,
use of agricultural chemicals, and the vul-
nerability of an aquifer will be investigated
in the statistical analysis of results from this
survey.
Because no complete list exists of the
rural, private water wells in the state, scien-
tists used a two-stage probability sampling
plan. In stage one, they randomly selected
200 land sections and developed a com-
plete list of all dwellings and private wells
within the rural area of each section. In
stage two, staff members randomly select-
ed approximately 340 private water wells
from the list of wells in the rural area of
each section containing such wells, ac-
quired permission to sample wells, and
conducted interviews with the users of the
wells.
Researchers are collecting samples
over a 13-month period, scheduled to
spread collections across all seasons and
periods for applications of pesticides and
fertilizers. In addition to data they acquired
from the well-user interview and well-site-
characterization form, they are compiling
soil and geologic data for each site.
Results of this statewide survey will pro-
vide the first statistically reliable estimates
of the extent of contamination caused by
agricultural chemicals in rural, private water
wells in Illinois. The survey should also pro-
vide some information on the factors affect-
ing contamination of private wells. By
identifying areas where private wells are
more vulnerable to contamination and by
identifying pesticides that are more likely to
cause contamination, the study may pro-
vide a basis for more accurate targeting of
future monitoring programs in the state....
In yet another project with the IDOA, the
Geological Survey is assisting in address-
ing the 1990 amendments to the Illinois
Pesticide Act which require the Department
of Agriculture to develop guidelines and
recommendations, including long-term
financial expenditures which may be neces-
sary to remediate contamination caused by
pesticides.
Through this reporting period, the ISGS
has completed a review of alternative sam-
pling plans for selecting specific agrichemi-
cal facilities for on-site assessments. Sci-
entists have performed an initial screening
of the potential for aquifer contamination at
50 randomly-selected facilities, based on
existing geologic mapping at a scale of
1:250,000. In addition, the Geological Sur-
vey has provided assistance in developing
technical standards for conducting phase 1
and 2 environmental site assessments at
20 agrichemical facilities. The actual eval-
uation and assessment of conditions and
operational practices at these facilities will
be conducted by other contractors....
Studies on fate of atrazine
Subsurface movement of atrazine, a her-
bicide, and de-ethylatrazine and deisopro-
pylatrazine, primary degradation products
of atrazine, are being studied to estimate
the relative contribution of surface-water
runoff and shallow groundwater discharge
to pesticide loadings in streams. A small
watershed in east-central Illinois is the focal
point of this study.
Atrazine and its degradation products
were present in water samples from the
stream throughout most of the year. Con-
centrations of atrazine in individual water
samples ranged from 4.9 micrograms per
liter in late May to less than 1 .0 microgram
per liter during June. The average con-
centration of atrazine in samples exceeded
one microgram per liter in the five sampling
periods from April 17 to May 29, 1991 , ex-
cept for samples collected on May 1 .
Atrazine was applied to cropland in the
watershed from late April through early
May. This high concentration of atrazine
coincided with increased surface-water
runoff and stream discharge in response to
more than nine inches of rainfall during the
month. The occurrence of these com-
pounds in water samples from the stream
during the remainder of the year may be
the result of the discharge of groundwater
into the stream, discharge of tile-drainage
water, or desorption (detachment) of atra-
zine from stream-bed sediments.
15
A mobile drill rig was
used to install eight
13-foot-deep nests,
six nests in the field
and two in the stream.
The six field nests in-
cluded a water-table
monitoring well and
three piezometers
(one to measure
depth of water table
and the other two to
measure water pres-
sure within the till and
the sand).
16
The adsorption (attachment) of atrazine
by surface soils is well understood, but few
studies exist on the movement of atrazine
in deeper materials containing low levels of
organic carbon. Research indicates that
this pesticide's adsorption by such materi-
als may be under estimated. Laboratory
measurements disclosed that the extent of
atrazine adsorption may be one to five
times greater than predicted by the organic-
carbon content, an observation consistent
with other studies.
A continuous soil core was collected to a
depth of four meters at each nest site when
the wells and piezometers were installed.
Samples from these cores will be used for
adsorption studies of atrazine.
Measurements have indicated that
atrazine does not desorb (detach) readily
during short-term intervals. As the organic-
carbon content increases, the degree of
irreversibility also increases. This lack of
reversibility may be the result of slow de-
sorption or a reaction of atrazine with the
organic matter to form chemical bonds.
However, once below the surface soil,
atrazine's subsequent migration will be
slightly retarded by adsorptive-desorptive
interactions, depending on the distribution
of organic matter in the subsurface and the
acidity or alkalinity of the groundwater.
Studies with de-ethylatrazine will begin
next fiscal year. This research is being
funded by the U.S. Department of Agricul-
ture's Cooperative State Research Service
through the Groundwater Research Con-
sortium of Southern Illinois University at
Carbondale....
And more
Researchers also evaluated the utility of
monitoring drainage-tile effluent for pes-
ticides as a potential alternative to the in-
stallation and monitoring of large networks
of groundwater-monitoring wells. They col-
lected samples from drainage tiles, soil-
water samplers, monitoring wells and soil.
Results demonstrate that pesticide con-
centrations in drainage-tile effluent can be
used to evaluate the leaching behavior of
these compounds in the field, provided cer-
tain information is known regarding the
layout of the tile system and the local
hydrogeologic setting....
To clarify potential problems of regional
contamination caused by agricultural chemi-
cals, the USEPA Region V also supported
the production of a Contamination Potential
Map of the Chicago Sheet, covering parts
of Illinois, Indiana, Ohio, Michigan and Wis-
consin. This map was produced in a
cooperative effort by the USGS and the
ISGS, using the USGS' texturally-based,
three-dimensional maps. Currently, the
USGS is statistically evaluating the validity
of information portrayed, comparing con-
tamination potential units on the map to ac-
tual contamination of wells by nitrates.
Again responding to the Groundwater
Protection Act, the Survey has generated a
map, "Potential for Aquifer Recharge in Illi-
nois," which shows recharge areas based
on depth to aquifers and surface-soil infiltra-
tion. It can also be used to evaluate the
potential for contamination of aquifers....
The ISGS and the ISWS, in cooperation
with the IEPA, are using the new recharge
map and a number of other geologic maps
in a detailed pilot study of the geologic and
hydrologic aspects of the Woodstock area.
The study will establish methodology for
making groundwater protection needs as-
sessments to be used in assisting local
governments with evaluating aquifer char-
acteristics and defining areas of potential
contamination.
Thus far, scientists at the Surveys have
compiled preliminary versions of cross sec-
tions, isopach maps of four aquifers that
were discovered in the area, a stack-unit
map of materials to a depth of 1 00 feet,
and a map depicting the potential for con-
tamination of aquifer materials for the
Woodstock 7.5-minute topographic Quad-
rangle. They are also statistically analyzing
the chemical data and drafting reports.
Pressure is mounting for more detailed
geologic mapping statewide. Such maps
are being used as tools to investigate and
solve environmental problems, aid in re-
source management, and help prioritize
geographic areas most in need of evalu-
ation, monitoring, or perhaps remedial
technology.
Geologic Mapping Provides
Problem-Solving Information
Because the Earth's materials are essential
to modern life and their consumption can
cause environmental problems, mankind
needs to understand their nature and dis-
tribution. After all, the populace lives and
depends on these materials, extracting
water and minerals from them; depositing
waste in them; constructing roads, dams,
and buildings from and on them; and is af-
fected by hazards, like earthquakes, land-
slides and subsidence, involving them.
Geologic maps provide information
which mankind can use to help solve its
many earthbound environmental and
resource-related problems. Such maps
Looking over a sand isolith map of Lake County to be used to help
site a landfill are Don McKay, senior geologist and head of the Geo-
logical Mapping and Digital Cartography Section, Lisa Smith and
Bob Pool, geologists. The map was prepared using GIS software.
illustrate the character of materials at or
below the ground's surface, depicting soils
of various types, sand or sandstones, silts
or siltstones, clays or shales, limestones or
dolomites, varieties of glacial deposits,
coals and other mineral resources, their
ages, physical character, and lateral and
vertical distribution.
How much information can be presented
on a geologic map? A map's scale deter-
mines the detail shown. The geology of the
entire state on one sheet of paper, even if it
is a large wall map, does not permit much
detail. On the 1 :500,000-scale geologic
map of Illinois, for example, one inch repre-
sents about eight miles on the ground; 1/32
inch, about the thickness of a heavy line,
equals 1 ,320 feet on the ground. Maps
that permit representation of greater detail
are the 1 :24,000-scale 7.5-minute topo-
graphic quadrangles. On these maps, one
inch represents 2,000 feet on the ground,
permitting about 20 times the resolution of
statewide 1 :500,000-scale maps. Although
a line 1/32-inch wide on the 1 :24,000-scale
map still represents about 62 feet on the
ground, this scale allows city blocks to be
shown without difficulty.
While regional geologic map coverage
of Illinois is available at scales from
1 :500,000 to 1 :250,000, a lack of funding
has prevented the development of state-
wide geologic maps at scales detailed
enough (1:24,000 to 1:100,000— one inch
equalling 1.6 miles) for today's planning
and decision-making purposes, focusing on
rapidly increasing environmental concerns
and continuing pressures for and from
economic development.
Such highly detailed geologic maps
often are required for decision making by in-
dustry in locating resources, siting facilities,
and undertaking construction projects.
Municipal, county, state, and federal
governmental agencies need the same
kinds of maps for planning purposes and
assessing competing land uses; selecting
areas where geologically appropriate sites
17
18
for landfills and even nuclear waste dis-
posal facilities are likely to occur; selecting
areas where facilities such as hospitals or
schools can be safely located; developing
zoning regulations; and assessing the
value of land. Private, public and govern-
mental sectors need these highly detailed
geologic maps for the development and
protection of groundwater resources and to
identify hazards and assess the potential
damage from earthquakes, landslides, sub-
sidence and coastal erosion.
The principal source of geologic maps
for Illinois is the ISGS by virtue of man-
dates of the General Assembly and the
Survey's tradition of investigating and
reporting on the geology of Illinois. While
statewide maps exist on regional scales,
only three percent of the state is covered
by published maps at the detailed 1 :24,000
scale required for many current applica-
tions. The only sizeable areas with ade-
quate coverage at that scale are the Illinois
Kentucky Fluorspar District of southeastern
Illinois, the adjacent coal-field area in
southern Illinois, and the Chicago area of
northeastern Illinois. These maps are ac-
companied by detailed geologic reports.
The Chicago-area maps were published in
the 1940s; the Fluorspar District maps, in
the 1 960s; and maps of the coal-field area,
in the 1 980s and 1 990s.
Mapping area, rich in resources
The latter maps are part of an ongoing
geologic mapping program that has been
supported since 1984 by the USGS and the
State of Illinois under the Cooperative Geo-
logic Mapping Program (COGEOMAP).
This region of southern Illinois, while rich in
some areas in such mineral resources as
coal, oil, gas and fluorspar, is underdevel-
oped. The geology of the southernmost
portion of the region is more complex than
other parts of the state, and its details are
only now beginning to be understood.
Through COGEOMAP, renewed efforts
by the Survey's mappers have located new
seams of coal. However, these are gener-
ally thinner and less easily mined than
other coals in the state, and their sulfur con-
tent is not as low as expected. Detailed
mapping also is changing geologic con-
cepts of the region in ways that could pro-
vide new tools for successful exploration of
oil and gas. Faults outside the Illinois Fluor-
spar Mining District have been mapped in
detail and are potential targets for mineral
exploration.
The original COGEOMAP program calls
for the publication of 16 7.5-minute geo-
logic quadrangles; six of these have been
published and three are currently in produc-
tion. Another four quadrangles in south-
western Illinois were added this year for
mapping by 1993.
Further expansion of the COGEOMAP
program in Illinois during this reporting per-
iod brings the mapping effort into the east-
central part of the state. The USGS has
awarded the Survey a contract to develop
an advanced methodology for three-dimen-
While in the field
working on the
Cooperative Geo-
logic Mapping
Project (COGEO-
MAP), a scientist
climbs a lime-
stone outcrop
along the Missis-
sippi River in the
Grand Tower
area.
sional mapping of Quaternary (glacial) de-
posits in the Champaign 1:100,000-scale,
1/2-by-1 -degree Quadrangle.
Through the Conterminous U.S. Mineral
Assessment Program (CUSMAP), a coop-
erative project among the USGS and the
State Geological Surveys of Illinois, In-
diana, Kentucky and Missouri, geologic in-
formation is being summarized on maps at
the 1 :250,000 scale (one inch equals ap-
proximately four miles) from an original
compilation at a 1 :1 00,000 scale for a
5,000-square-mile-area of Illinois south of
Benton and DuQuoin. This project pro-
vides detailed geological, geochemical and
geophysical (seismic, gravity and magnet-
Barb Stiff, GIS specialist, Mike Sargent, seated, geologist in the
Basin and Crustal Analysis Section, and Jim Baxter, senior geologist
and head of the Industrial Minerals and Metals Section, examine a
map showing potential veins of fluorspar in Illinois. Assessment
maps for about 20 commodities and many intermediate maps were
produced digitally for a Paducah CUSMAP meeting.
ic) studies in regions known to contain or
have potential for mineral deposits such as
fluorspar, lead, zinc and industrial minerals
(sand, gravel, limestone) and others. Its
goal is to develop sufficient knowledge to
determine the likelihood of finding new
mineral resources or extensions of known
deposits in the Paducah 1 -by-2-degree
Quadrangle, covering approximately 7,500
square miles in the states involved.
The ISGS has coordinated much of this
research effort and data input and, with the
USGS, has taken the lead in developing a
computer data base for the ISGS' Geo-
graphic Information System (GIS) that incor-
porates new techniques in computer-
assisted spatial data analysis and cartog-
raphy for the Paducah CUSMAP project.
Scientists have completed research and ac-
quisition of data and, using the GIS, have
prepared maps showing areas of high,
moderate, and low potential for mineral dis-
covery. They will release results of the
resource assessment at a public meeting in
January 1992.
GIS integrates, synthesizes data
The efficacy of the computer technology for
assessing mineral potential was demon-
strated in April 1991 at a workshop held in
Champaign. As the name GIS implies, the
geographic or spatial nature of information
is fundamental. Geographic location of
natural and cultural features provides a
framework in which diverse data can be
compiled and integrated to discover rela-
tionships and generate new information.
The GIS' functions of integration and anal-
ysis provide a mechanism for combining in-
formation, testing multiple scenarios, and
presenting the results in map form that is
easy to understand. Thus, the GIS can be
an invaluable tool for integrating and syn-
thesizing information required to make criti-
cal choices and solve problems that face
Illinois.
In using the GIS as a tool to assess re-
source potential for CUSMAP, geologists in-
itially wanted to translate all available data
into a digital format and use the GIS to cal-
culate the relative potential for each type of
mineral deposit. Thus, they developed tech-
niques for digitizing maps and translating
numerous types of data into the GIS format.
To produce a map depicting an area of
relative mineral potential, the scientists
created a digital model of deposits for each
mineral, using descriptive deposit models
that defined diagnostic criteria and quan-
tified numerous criteria describing ore
deposits. For example, permissive, neces-
sary and critical criteria were specified in
many of the descriptive models. While
creating quantified digital models from the
descriptive models, staff members needed
a numeric weighting scheme to reflect the
relative importance of each criterion. This
process involved selecting the most impor-
tant diagnostic criterion necessary for the
occurrence of the mineral deposit being
considered and assigning its presence an
arbitrary high-value weight. Other criteria
were assigned lesser weights relative to
their individual importance in the model.
Weighted criteria were then combined.
When all of the layers of a deposit
model were combined using the GIS over-
lay technique, areas of relative resource
potential were drawn. Based on the total
model weight assigned to each area,
those with higher and lower potential for
mineral occurrence could be identified.
19
The purpose of these maps is to highlight
areas which might have mineral resour-
ces— areas which could be targets for fu-
ture research and exploration.
Upon completion of the project, the
ISGS with the USGS will publish a series of
reports on the geology and mineral resour-
ces of the Paducah Quadrangle. These
will include new and innovative compila-
tions of resource data related to coal, oil,
gas, and the industrial mineral and metal
resources; detailed surficial, bedrock and
subsurface maps and cross sections; topi-
cal studies; and a general assessment of
the mineral potential of the area. Avail-
ability of this information coupled with the
20
Bob Pool, GIS geologist, views a model created for the
CUSMAP study.
development of new theories and models
could make southern Illinois more attractive
for mineral exploration and entrepreneurial
activity.
Rock units, structures identified
Besides showing topographic elevations
and geographic features, a detailed geo-
logic map uses various colors and symbols
to show the relationships of rock units that
are exposed at the surface. One such
map, the Equality Quadrangle, covering an
area in Gallatin County near the village of
Equality, also shows the location of major
coal seams and where the coals have been
mined out. By knowing the lateral extent
and thickness of the coals and what's been
mined, one can estimate the quantity of
coal remaining. This detailed map also
identifies structures such as faults. In near-
by areas, faults have trapped oil or have
contributed to the formation of other min-
eral resources such as fluorspar. Thus,
these maps convey information useful in
assessing the potential for discoveries of oil
and gas and other mineral resources. They
also provide basic information and ideas
seful to industry in exploring and develop-
ing the state's resources.
Detailed geologic maps can be especial-
ly helpful in resolving issues related to the
environment, for example, in protecting
groundwater resources from contamination.
A map of Boone and Winnebago counties,
originally compiled at the scale of one inch
equals 2,000 feet, was printed at the more
reduced scale of 1 :62,500— one inch
equals about a mile. This particular map
was derived from the detailed geological
map, called a stack-unit map, which shows
the nature of earth materials down to a
depth of 20 feet. The derivative map
depicts areas more susceptible to the con-
tamination of groundwater. In particular,
sands and gravels and the fractured
bedrock (a significant aquifer in the area)
occurring within 20 feet of the surface are
differentiated from areas less susceptible —
the more impermeable glacial materials
(tills) that are more favorable for landfills.
These tills act as barriers to contamination
of groundwater resources.
Unfortunately, before the need for this
type of information became known and
before these maps could be developed for
Boone and Winnebago counties, numerous
landfills had already been located in the
areas most susceptible to the contamina-
tion of groundwater. Leakage from existing
landfills into groundwater was virtually as-
sured. To date, some four Superfund
Sites, subject to clean up, have been iden-
tified in Winnebago County. Cleaning up
those sites will be very costly. (Published
figures indicate that the average cost of
cleaning up a Superfund Site is between
$20 million and $30 million.) If these kinds
of geologic maps had been available when
applications for these disposal sites were
being considered, the need for and cost of
clean up might have been avoided. Landfill
applicants and public officials would have
known the more geologically favorable
areas and could have located the landfills
accordingly. The cost of the project to
develop this map for the two counties was
approximately $250,000 — an investment,
which, if made even earlier, could have
helped avoid future multi-million-dollar-
clean-up costs at the Superfund Sites,
giving some appreciation of the pay back
possible from this type of detailed geologi-
cal mapping.
Benefits, costs analyzed
In a definitive study for Boone and Winne-
bago counties, the Survey quantified the
benefits of detailed geologic mapping.
Staff members compared the benefits to
the cost of mapping discussed above. The
return on an investment of $300,000 in
1990 dollars was about 23 to 54 times the
investment for the best-case scenario and
5 to 1 1 times the investment for the worst-
case scenario. The most probable case in-
dicated benefit/cost ratios of 1 1 .7 to 27.2.
Benefits were calculated from avoided
costs associated with the clean up of land-
fills and industrial disposal sites. The bene-
fit/cost analysis excluded other benefits
that are not currently quantifiable such as
identifying and recovering the Earth's
resources and providing basic data to in-
dustry and government for siting facilities —
data indicating water supplies, foundation
conditions, and areas suitable for the instal-
lation of septic tanks. Such benefits would
increase the benefit/cost ratios significantly,
just as they have in Kentucky.
Over an 18-year period in the 1960s and
1970s, Kentucky was mapped at this de-
tailed scale at a cost of $21 million. Since
then, the maps have been used extensive-
ly. The Kentucky Geological Survey esti-
mates that the cost of the mapping has
been repaid to the state at least 50 times
over, coming from new coal mines opened
in areas where new coal resources were
mapped and from new oil and gas wells
drilled into oil and gas reservoirs near faults
that had previously been unknown. In addi-
tion, the pay back has come from savings
derived from locating new highways that
avoided landslide-prone areas. The maps
also found widespread use in siting farm
ponds and industrial facilities in Kentucky.
County officials listen to Rob Krumm, center, geologist, and Curtis
Abert, assistant, seated, of the Geologic Mapping and Digital Cartog-
raphy Section, who are explaining computer mapping used for regional
screening to determine areas geologically capable of being landfill sites.
The ISGS prepared a report, "Geologic
Mapping for the Future of Illinois," for the Il-
linois Senate Committee on Geologic Map-
ping and presented it in July 1 991 . This
report included a detailed analysis of geo-
logic mapping needs and prioritized the
mapping of the 1 ,073 7.5-minute quad-
rangles in the state. Based on prioritized
needs and uses, detailed geologic maps
are required in Illinois to:
• ensure sufficient present and future
supplies of groundwater;
• protect groundwater in areas of high
usage and help assess the impact of
agricultural chemicals on the quality
of groundwater;
• plan landfill sites in the most popu-
lated counties or rapidly developing
corridors with high priority given where
capacity is most limited and where
county plans indicate imminent need
for a suitable site;
• assess geologic and related hazards,
especially seismic risk and threat of
landslides, coastal erosion and sub-
sidence;
• select sites for development, especial-
ly in areas of rapid growth;
• permit comprehensive assessment of
strategic and critical minerals;
• identify location and extent of deposits
of sand, gravel, limestone, dolomite
and other industrial minerals for the
entire state, giving highest priority to
metropolitan areas where construction
needs are greatest;
• locate deposits of low- to moderate-
sulfur coal;
• determine the nature and structure of
bedrock, useful, for example, in the ex-
ploration for and development of oil
and gas;
• introduce the public to Earth Science
in parks, national corridors and other
recreational areas.
Such maps are required to aid in
economic development, environmental
protection and risk assessment. The
recommended geologic mapping program,
designed to meet these expressed needs
in priority order, is a long-term, multi-year
effort, requiring dedicated funds. The
recommended level of state funding for this
program is $1.1 million per year over a
period of 50 years.
21
Mapping, very restricted
Currently, the geologic mapping effort
operated by the ISGS under the General
Revenue Funds includes a staff of 2.9 full-
time staff equivalents with an annual expen-
diture of approximately $170,000. During
the decade of 1982-1991, the ISGS will
have mapped 43 7.5-minute quadrangles
and published them at a scale of one inch
equals one mile or more detailed under the
COGEOMAP and pollution prevention
programs. Included are about 16 quad-
rangles in Boone and Winnebago counties,
about 18 in Champaign County, and nine in
the coal-field area of southern Illinois. The
22
Geologist Joe Devera examines a fossilized log in a bedrock out-
crop in southern Illinois.
total effort is small and restricted geographi-
cally and functionally. At this rate, more
than 200 years would be required to com-
pletely map Illinois at a detailed scale. The
pressures of environmental and economic
concerns will not permit such a slow time-
table in Illinois.
Similar needs exist in every other state
except Kentucky and possibly Massachu-
setts, Rhode Island and Puerto Rico, which
have been mapped at the suggested de-
tailed scales. Mapping Kentucky and the
other states was aided by the availability of
detailed topographic maps at a scale of
one inch equaling 2,000 feet. These maps
are now available for all of the lower 48
states, thus making more detailed geologic
mapping feasible.
Obviously, a state and federal program
of geological mapping is needed. Pay back
may be expected on the basis of saving
clean-up costs of disposal sites alone.
Other benefits will accrue in the delineation
of mineral resources that will aid in building
and rebuilding the nation's infrastructure; in
the delineation of groundwater resources
and their potential for contamination; and in
the delineation of geologic hazards and
their risk to public health, safety and proper-
ty. Proposed legislation, if enacted, will pro-
vide the basis for a sound investment in the
future of the nation and Illinois.
Thus, passage is needed of the Geo-
logic Mapping Act of 1991 , a bill that has
been introduced in Congress to facilitate
the production of the required detailed
maps. The key element of the proposed
program is the State Geologic Mapping
Component, calling for matched state and
federal funds, starting at $15 million and
stepping up to $25 million per year in the
fourth year. A multi-year effort, the pro-
gram requires secure, dedicated funds.
The House passed its version of the bill in
late 1991. The Senate and Congress are
expected to pass the legislation in the cur-
rent session. Support of the appropriation
is needed to implement the authorizing
legislation.
Parallel legislation at the state level is re-
quired to ensure proper coordination of the
state and federal programs and to imple-
ment a prudent program to meet Illinois'
needs in a timely way.. .to ensure that this
state is in a position to participate and re-
ceive its share of federal funds. A federal
appropriation at the $15 million level and
growing to $25 million should provide be-
tween $700,000 to $1,100,000 per year in
federal funds to Illinois for mapping. The
addition of state matching funds may per-
mit Illinois to be mapped at a scale of one
inch equals 2,000 feet in about 25 to 35
years, depending on the level of funding.
Thus, time can be reduced in half with
federal-state matching funds and perhaps
to 17 or 18 years with contributions from
other beneficiaries such as local and coun-
ty governments and industry in Illinois.
A state and federal program of geologi-
cal mapping is in the national interest.
Benefit/cost studies indicate that geologic
maps will save the nation and state money.
The proposed legislation, if enacted, will
provide the basis for a sound investment in
the future of the United States and Illinois.
Future Challenges Abound
Research investigations and service efforts
of the ISGS address the state's issues or
anticipated needs, taking trends into ac-
count. Such trends include a greater con-
cern for the environment and quality of life.
In fact, the Governor's office asked ENR to
develop a program to assess the environ-
ment in Illinois. Based upon a report by the
Science Advisory Board of the USEPA, the
Geological Survey and the other scientific
divisions of ENR evolved a plan to conduct
and report on a critical trends assessment
of environmental elements in the state.
This Critical Trends Assessment Project
will use the extensive data base for Illinois
From the left, Jimmy Cooper, craftsman, Dave Moran, chemical en-
gineer, and Massoud Rostam-Abadi, senior chemical engineer,
prepare to operate the process optimization unit which will provide
engineering data for the scale-up of the Geological Survey's process
producing high-surface-area hydrated lime. This product will increase
the effectiveness of dry-injection systems for decreasing sulfur-dioxide
emissions, producing results, in pilot-scale tests, sufficient to bring
Illinois' coals into compliance with the goals of acid rain legislation for
the year 2001. A patent covering the process has been applied for.
and the computerized IGIS to advance the
management of the state's environment
and natural resources into the next century.
Two goals are foremost: to develop an in-
tegrated environmental data base, merging
economic, social and natural resource infor-
mation for analyses by the IGIS; and pro-
duce a state-of-the-environment report for
Illinois. The environmental trends which
evolve from the analyses can be synthe-
sized into a report written for the general
public that will provide an overview of the
state's environment and the implications for
human health, economical health, and
quality of life. More importantly, the report
that results from the analyses will help as-
sure that environmental policy is based
upon a comprehensive picture of trends
and rate of change. A more meaningful
perspective should evolve as the Survey
and the state work toward both a healthy
economy and a healthy environment.
Toward these goals, near-term challen-
ges for the Geological Survey, as one of
the state's earth agencies, include:
• Transfer of the high-surface-area
(HSA) hydrated lime process to in-
dustry
Continued development of the HSA hy-
drated lime technology and transfer of its
technology to the commercial market is re-
quired as rapidly as possible to increase
the use of Illinois' coal by utilities, its major
market, threatened by acid-rain-reduction
goals that restrict sulfur emissions. This
post-combustion cleaning process, devel-
oped by the ISGS' researchers, will in-
crease the effectiveness of dry-injection
systems for decreasing sulfur-dioxide emis-
sions, having achieved superior sulfur-
dioxide removal results over other hydrates
tested (up to 90 percent increased effective-
ness).
23
24
• Maintaining the marketability of
Illinois' coal resources
Programs to decrease sulfur-dioxide emis-
sions have been well established at the
ISGS, including research to decrease the
sulfur and mineral-matter content (pre-
combustion cleaning), research to more
economically remove sulfur dioxide from
combustion gases such as the lime hy-
drate, and programs to encourage and aid
researchers throughout the world to help
solve problems associated with the use of
Illinois' coal.
Through continued research, the ISGS
looks forward to breakthroughs on liquids
from coal by means of mild gasification;
lignin-enhanced depolymerization of coal;
and other projects needed to help maintain
viable markets for Illinois' coal.
• Stable state funding for oil recovery
research
Stable, long-term funding must be imple-
mented to support the state's share of the
promising state-federal cooperative re-
search program on improved and en-
hanced oil recovery, highlighted in this
report.
• Stable state funding for the IGIS
Stable, long-term funding must be devel-
oped to support the continued operation
and maintenance of the IGIS and to sup-
port the continued development of the
various computerized data bases required
by its users.
• Groundwater protection research
program
Continued research and enhanced financial
support is needed to meet the mandates of
the Illinois Groundwater Protection Act, es-
pecially projects directed toward developing
an understanding of the present quality of
groundwater, to establish a base line
against which to compare any future
changes in its quality, and to protect this
vital resource.
• Contributions of the ISGS to waste
management programs
Greater efforts are needed to gain recogni-
tion and use of geologic maps and the GIS
in providing technical assistance for landfill-
site screening as an integral part of pro-
grams in solid waste management and to
recognize the continued need for siting
some landfills. Even if programs for recy-
cling and waste reduction are highly suc-
cessful, some waste will always be
generated.
• Funding for a statewide geologic
mapping program
An initiative must be implemented for a
fully-funded program to map the geology of
Illinois in the detail required to respond to
modern needs for geological information.
Illinois' program should include a clear
authorization for the expenditure of at least
$1.1 million per year in 1990 dollars, with or
without matching funds from federal or
other sources.
Looking ahead three to five years,
longer-term challenges to the ISGS include:
• Rebuilding the infrastructure
A program needs to be implemented to find
and characterize the aggregate materials
and other industrial and metallic mineral
resources that will be required to rebuild
the crumbling infrastructure. Such informa-
tion can be a significant outgrowth of the
geologic mapping initiative.
• Environmentally responsible
development and use of fossil fuels
Research must be continued on the en-
vironmentally responsible development and
use of fossil fuels to sustain the economy
of southern Illinois. While alternative fuels,
like ethanol and hydrogen, and alternative
energy sources, like solar and wind power,
will be an increasingly important part of the
overall energy supply for the United States,
coal and liquid hydrocarbons will continue
to be major sources of energy for the fore-
seeable future. Because no other energy
sources occur in such a convenient form
and at such a low cost, they will continue to
be the touchstones against which the eco-
nomic viability of other energy sources will
be measured.
• Broad-based research program on
global climate change
A need exists to develop a broad-based,
integrated, department-wide research pro-
gram on global climate change and its po-
tential impacts on the environment and the
economy of Illinois. The program should
not only examine observable changes in
the climate and atmospheric composition,
but it should also examine the manner in
which activities of industries in the state
affect the climate and atmosphere and
whether proposed remedial actions will
have an impact on the accumulation of
greenhouse gases. The Department of
Energy and Natural Resources is uniquely
equipped to carry out the kind of full life-
cycle analyses necessary to determine
whether a proposed energy conservation
strategy or alternative fuel production
method is neutral or beneficial in terms of
reducing greenhouse-gas emissions. The
potential impacts on Illinois' biological diver-
sity and groundwater quality of altered
agronomic practices for purposes of bio-
mass fuel production (derived from ferment-
ing wood or agricultural wastes) also
require close examination.
• Improved technology transfer
program
A program needs to be implemented to sig-
nificantly enhance the ability of the ISGS to
transfer its technologies and other scien-
tific information to the people who need it.
Minerals engineer Hank Ehrlinger monitors the 12-foot-tall Deister
flotation column at the Applied Lab. With column flotation, waste
material from coal preparation plants is fed in slurry form into this
type of column. A mixture of tiny air bubbles, chemical reagents
and water is added. The fine coal particles adhere to the air bub-
bles and rise to the top of the column where they are removed as a
concentrate. This method generates coal that contains more than
13, 000 Btu per pound. The resulting coal slurry may be ideal for
use in coal gasification because it is ready to be made into a
gasifier feed slurry with little additional processing.
In addition to fundamental improvements in
the Survey's abilities to provide computer
access to major data files, staff, equipment
and space are required to allow more fre-
quent workshops, seminars and other free
forums as a means of conveying the Geo-
logical Survey's data and research informa-
tion to the public.
• Public education on the importance
of independent scientific research
for environmental and mineral
resource issues
The Survey must speak for the importance
of maintaining a strong, politically inde-
pendent, non-regulatory scientific research
arm, capable of providing state and local
governmental officials with unbiased scien-
tific analysis of the increasingly complex en-
vironmental and mineral resource issues
confronting Illinois.
Illinois faces serious issues concerning
its water, land, energy and mineral resour-
ces. Can it ensure an adequate supply of
these resources? Are these resources
being properly used? Are other uses
possible that would help stimulate the
economy? Are there new emerging tech-
nologies that will help in striving toward
economic and environmental health?
Environmental issues related to the
management and protection of Illinois'
resources abound — issues that involve
public safety, health and recreation; agri-
culture; and the state's infrastructure. Is
groundwater contamination a problem? If
so, where? How do we protect our ground-
water? How should we manage wastes to
avoid contamination? How do we produce
clean coal? Can natural or man-caused
hazards be prevented or mitigated? Can
we use Earth's processes and resources to
our advantage to improve conditions and
enhance the quality of life?
Responses to these and similar ques-
tions depend on continually increasing
knowledge and understanding of our sur-
roundings— of the structure, resources and
dynamics of the Earth— the detailed geol-
ogy of this state. The public and govern-
mental officials require this type of scientific
information to make informed decisions
about the wise use of the finite and pre-
cious resources — decisions which will af-
fect the standard of living, economic growth
health and safety of Illinois' residents and
can have an impact on the nation as well.
To this end, the ISGS is mandated to pro-
vide the geologic knowledge and informa-
tion to help answer such questions.
25
Writer/Editor: Sue Muckensturm
Graphic Designer: Sandra Stecyk
Photographer: Joel Dexter
) printed on recycled paper
Printed by authority of the State of Illinois/1992/3500